Genetically modified muscle cells which express neurotrophic factors

ABSTRACT

An isolated muscle progenitor cell being MyoD positive, CD34 negative and CD45 negative is disclosed. The muscle progenitor cell is genetically modified to express at least one neurotrophic factor. In addition, cell populations are disclosed, comprising at least four subpopulations of muscle cells each being genetically modified to express a different neurotrophic factor, wherein said neurotrophic factor is selected from the group consisting of glial derived neurotrophic factor (GDNF), insulin growth factor (IGF-1), vascular endothelial growth factor (VEGF) and brain-derived neurotrophic factor (BDNF). Uses of the cell populations are also disclosed.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/180,152 filed on Jun. 13, 2016, now abandoned, which is a division ofU.S. patent application Ser. No. 14/002,782, filed on Sep. 3, 2013, nowU.S. Pat. No. 9,365,828, which was a National Phase of PCT PatentApplication No. PCT/IB2012/050976 having International Filing Date ofMar. 1, 2012, which claims the benefit of priority under 35 USC 119(e)of U.S. Provisional Patent Application No. 61/448,712 filed on Mar. 3,2011. The contents of the above applications are all incorporated byreference as if fully set forth herein in their entirety.

SEQUENCE LISTING STATEMENT

The Sequence Listing in ASCII text file format of 47,935 bytes in size,created on Mar. 14, 2019, with the file name “2019 Mar.14SequenceListing-OFFEN3B,” filed in the U.S. Patent and TrademarkOffice on even date herewith, is hereby incorporated herein byreference.

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof relates togenetically modified muscle cells for the treatment of neurodegenerativedisorders.

Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease,was first described in 1869 by a French neurologist, Jean MartinCharcot. This is a progressive, lethal disease that leads todegeneration of upper and lower motor neurons. Death of the upper motorneurons found in the motor cortex in the brain, leads to spasticity,hyperexcitability of reflexes and the appearance of pathologicalreflexes. The death of the lower motor neurons, which is found in thebrain stem and in the spinal cord, leads to weakness and atrophy of themuscles followed by progressive paralysis.

ALS has a worldwide prevalence of 1-2 per 100,000, and mortality iscaused within 3-5 years of the onset of the disease due to respiratoryfailure. ALS occurs mainly in adults (45-60 of age), and most cases aresporadic, although 5 to 10% of ALS cases are inherited in an autosomaldominant pattern of which about 20% are caused by a mutation in theCu/Zn superoxide dismutase (SOD1) gene on chromosome 21. The diseaseresults from the over-activity of the SOD1 gene and not from the damagein its antioxidant activity. The etiology of sporadic ALS is unknown,although it is generally believed that sporadic and familial ALS mayshare pathological mechanisms.

The pathophysiology of the disease includes a reduced secretion ofneurotrophic factors (NTFs), protein aggregations, malfunctioning of themitochondria, rupture in the axonal passage, destruction in the calciummetabolism, changes in the skeletal proteins, high levels of glutamateand oxidative damage. Preventing or slowing motor neurons degenerationand death in ALS are critical goals of future therapies, as are means ofenhancing axonal regeneration.

Several studies concerning peripheral nerve pathology have demonstratedthat neurotrophic factors play an important role in the development,maintenance and regeneration of the nervous system. The brain derivedneurotrophic factor (BDNF) was shown to prevent the loss of motor unitsand to contribute to the maintenance of muscle mass when administered tothe hind limb muscles of mice after peripheral nerve injury. The glialderived neurotrophic factor (GDNF) and the insulin growth factor 1(IGF-1) are two of the most potent survival factors known for peripheralneurons. Several studies have shown that both GDNF and IGF-1 can preventneuronal degeneration in mice and rats after axotomy, as well as theprogrammed cell death of motor neurons during development [3, 6-9]. Inthe SOD1^(G93A) transgenic mice model for amyotrophic lateral sclerosis(ALS), overexpression of GDNF and/or IGF-1 in muscles, resulted inhyperinnervation of the muscles by motor neurons [3, 6-13]. Moreover,GDNF is important for neuron branching at the NMJ and for modulatingsynaptic plasticity [14]. Increased expression of GDNF in the muscles ofSOD1^(G93A) transgenic mice delays disease onset, improves locomotorperformance, and increases their lifespan. In addition, the survival ofmotor neurons is increased when GDNF levels in the muscles ofSOD1^(G93A) transgenic mice are high. The vascular endothelial growthfactor (VEGF) is another factor contributing to the pathogenesis of ALSand the increased expression of VEGF in motor neuron of SOD1^(G93A)transgenic mice, augmented their survival and enhanced motor performance[15-16]. Moreover, intracerebroventricular administration of VEGF in arat model of ALS, dramatically increased motor neuron survival and anintraperitoneal injection of VEGF led to the preservation of NMJs[17-18]. Unfortunately, clinical trials of systemic or intrathecaladministration of growth factors to ALS patients have not beeneffective, probably due in part to their short half-life, lowconcentrations at target sites, and high incidence of side effects[10-11].

Sarig et al., [Stem Cells 2006; 24: 1769-1778] teaches isolatedpopulations of muscle progenitor cells (MPCs).

Mohajeri et al [Human Gene Therapy, 10:1853-1866 (Jul. 20, 1999) teachesthe use of primary myoblast cells genetically modified to express GDNFfor the treatment of motor neuron diseases.

U.S. Patent Application No. 20050238625 teaches the use of skeletalmuscle cells genetically modified to express neurotrophic factors forthe treatment of nerve diseases.

U.S. Patent Application No. 20030161814 teaches the use of skeletalmuscle cells genetically modified to express GDNF for the treatment ofmotor neuron diseases.

SUMMARY OF THE INVENTION

According to an aspect of some embodiments of the present inventionthere is provided an isolated cell population, comprising at least foursubpopulations of muscle cells, each of the at least four subpopulationbeing distinct in that they are genetically modified to express adifferent neurotrophic factor, wherein the neurotrophic factor isselected from the group consisting of glial derived neurotrophic factor(GDNF), insulin growth factor (IGF-1), vascular endothelial growthfactor (VEGF) and brain-derived neurotrophic factor (BDNF).

According to an aspect of some embodiments of the present inventionthere is provided an isolated muscle progenitor cell being MyoDpositive, CD34 negative and CD45 negative, genetically modified toexpress at least one neurotrophic factor.

According to an aspect of some embodiments of the present inventionthere is provided a method of treating a nerve disease or damage,comprising administering to a subject in need thereof a therapeuticallyeffective amount of the isolated cell population described herein,thereby treating the nerve disease or damage.

According to an aspect of some embodiments of the present inventionthere is provided a method of treating a nerve disease or disorder in asubject, comprising introducing into the muscle cells of the subject afirst polynucleotide which encodes a first neurotrophic factor, a secondpolynucleotide which encodes a second neurotrophic factor and a thirdpolynucleotide which encodes a third neurotrophic factor, each of thefirst, the second and the third neurotrophic factor being mutuallydistinct, thereby treating the nerve disease or disorder.

According to an aspect of some embodiments of the present inventionthere is provided a method of treating a nerve disease or damage,comprising administering to a subject in need thereof a therapeuticallyeffective amount of an isolated population of muscle progenitor cells,the muscle progenitor cells being MyoD positive, CD34 negative and CD45negative, genetically modified to express at least one neurotrophicfactor, thereby treating the nerve disease or damage.

According to some embodiments of the invention, the muscle cellscomprise progenitor cells.

According to some embodiments of the invention, the muscle progenitorcells comprise skeletal muscle progenitor cells.

According to some embodiments of the invention, each of the at leastfour subpopulations are present in substantially equal amounts.

According to some embodiments of the invention, each of the at leastfour subpopulations are present in alternate ratios.

According to some embodiments of the invention, each of the at leastfour subpopulations is genetically modified to express a singleneurotrophic factor.

According to some embodiments of the invention, the isolated muscleprogenitor cell is isolated by at least two rounds of differentialplating, wherein a first round of the differential plating is effectedon plastic plates and a second round of the differential plating iseffected on a plate coated with a substance selected from the groupconsisting of collagen, gelatin and poly-lysine.

According to some embodiments of the invention, the at least oneneurotrophic factor is selected from the group consisting of glialderived neurotrophic factor (GDNF), nerve growth factor (NGF), vascularendothelial growth factor (VEGF), brain-derived neurotrophic factor(BDNF), neurotrophin-3 (NT-3), neurotrophin-4/5, Neurturin (NTN),Persephin, brain derived neurotrophic factor (BDNF), artemin (ART),ciliary neurotrophic factor (CNTF), insulin growth factor-I (IGF-1) andNeublastin.

According to some embodiments of the invention, the neurotrophic factoris selected from the group consisting of glial derived neurotrophicfactor (GDNF), vascular endothelial growth factor (VEGF), brain-derivedneurotrophic factor (BDNF) and insulin growth factor-I (IGF-1).

According to some embodiments of the invention, the isolated muscleprogenitor cell is an adult, muscle progenitor cell.

According to some embodiments of the invention, the isolated muscleprogenitor cell is a skeletal muscle progenitor cell.

According to some embodiments of the invention, the isolated muscleprogenitor cell expresses at least two of the GDNF, VEGF, BDNF andIGF-1.

According to some embodiments of the invention, the isolated muscleprogenitor cell expresses each of the GDNF, VEGF, BDNF and IGF-1.

According to some embodiments of the invention, the method furthercomprises introducing into the muscle cells of the subject a fourthpolynucleotide which encodes a fourth neurotrophic factor, each of thefirst, the second, the third and the fourth neurotrophic factor beingmutually distinct.

According to some embodiments of the invention, the first neurotrophicfactor is GDNF, the second neurotrophic factor is VEGF, the thirdneurotrophic factor is BDNF and the fourth neurotrophic factor is IGF-1.

According to some embodiments of the invention, the method is effectedin vivo.

According to some embodiments of the invention, the method is effectedex vivo.

According to some embodiments of the invention, the administering iseffected by transplanting the isolated population of muscle cells intothe muscle of the subject.

According to some embodiments of the invention, the firstpolynucleotide, the second polynucleotide and the third polynucleotideare comprised in a single nucleic acid construct.

According to some embodiments of the invention, the firstpolynucleotide, the second polynucleotide and the third polynucleotideare each comprised in a different nucleic acid construct.

According to some embodiments of the invention, the isolated populationof muscle cells are for use in the treatment of a nerve disease ordamage.

According to some embodiments of the invention, the nerve disease is aneuromuscular disease.

According to some embodiments of the invention, the nerve disease is amotor neuron disease.

According to some embodiments of the invention, the nerve damage isselected from the group consisting of peripheral nerve injury,peripheral nerve inflammation, autonomic nerve injury, pelvic nervedamage, burn, blunt trauma, back injury, back pain and sciatica.

According to some embodiments of the invention, the neuromusculardisease is selected from the group consisting of a spinal muscularatrophy, a amyotrophic lateral sclerosis (ALS), a Werdnig Hoffmandisease, a Charcot-Marie tooth disease, multiple sclerosis, myastheniagravis, muscular dystrophy and a myositis.

According to some embodiments of the invention, the motor neuron diseaseis selected from the group consisting of amyotrophic lateral sclerosis,primary lateral sclerosis (PLS), pseudobulbar palsy and progressivebulbar palsy.

According to some embodiments of the invention, the cells are autologouscells.

According to some embodiments of the invention, the cells arenon-autologous cells.

According to some embodiments of the invention, the neuromusculardisorder is ALS.

Unless otherwise defined, all technical and/or scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which the invention pertains. Although methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of embodiments of the invention, exemplarymethods and/or materials are described below. In case of conflict, thepatent specification, including definitions, will control. In addition,the materials, methods, and examples are illustrative only and are notintended to be necessarily limiting.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

Some embodiments of the invention are herein described, by way ofexample only, with reference to the accompanying drawings. With specificreference now to the drawings in detail, it is stressed that theparticulars shown are by way of example and for purposes of illustrativediscussion of embodiments of the invention. In this regard, thedescription taken with the drawings makes apparent to those skilled inthe art how embodiments of the invention may be practiced.

In the drawings:

FIGS. 1A-1K are graphs and photographs illustrating that rat and mousemuscle progenitor cells (MPCs) express and secrete neurotrophic factors.MPCs transfected with the neurotrophic genes BDNF (rat: A-B, mouse:H-I); GDNF (rat: C-D, mouse: J-K); VEGF (rat: E-F) and IGF-1 (rat: G) asmeasured by immunohistochemistry and ELISA.

FIGS. 2A-2C illustrate MPCs-mix (also referred to herein as MPCs-NTF)conditioned media protects motor neuron cell line (NSC-34) in cultureagainst hypoxic stress. After 48 hours in hypoxic environment, thecombination of the cells' conditioned media protects NSC34 cellsviability (rat MPCs-mix;A; mouse MPCs-mix: B, C. *p<0.05, **p<0.01).

FIG. 3 illustrates that rat MPCs-mix cells inoculation after sciaticnerve injury in rats, rescue the motor functioning. One day aftermechanical crush of the right hind limb, rat MPCs expressing each one ofthe four NTFs, combination of—NTF, GFP or PBS were inoculated into theinjury site. Motor recovery was examined by rotorod test and presentedby time spent on rod. In rats injected with combined MPCs-mix, motorfunction measured by rotorod was markedly preserved comparing to theother treatment and control groups. (n=9, *p<0.05 as determined by ANOVAtest).

FIG. 4 is a bar graph illustrating restoration of nerve conductionfollowing rat MPCs-mix inoculation. Four days following rat MPCsexpressing one of the four NTFs, combination of MPCs-mix, MPCs-GFP orPBS transplantation into sciatic nerve crush site, nerve conduction wastested by electromyography. Compound muscle action potential presentedas a ratio between the injured and uninjured hind limbs (n=3, means±SEM,**p<0.01 as determined by student t-test).

FIGS. 5A-5B illustrate that RMPCs NTF transplantation preservesinnervated neuromuscular junctions. Two weeks following sciatic nervecrush and transplantation of combination rat MPCs-mix or MPCs-GFP ratswere sacrificed. Hind limbs muscles were double stained using alphabungarotoxin (green) and anti-synaptophysin antibodies (red).Representative image of hind limb muscle section transplanted with ratMPCs-mix (A). Quantification of integrated NMJs (B) (n=5, means+SEM,*p<0.05, determined by student t-test).

FIGS. 6A-6D are photographs illustrating that rat MPCs-mix expressingneurotrophic factors in transplanted muscles. Two weeks followingsciatic nerve crush and transplantation of rat MPCs-mix, rats weresacrificed. Hind limb muscles sections were stained with antibodiesagainst BDNF (A); GDNF (B); IGF-1 (C) and VEGF (D).

FIGS. 7A-7B illustrate that mouse MPCs-mix cells transplantation intoSOD1 transgenic mice significantly delay symptoms onset. At 87 days, nosignificant difference was observed among experimental groups. Over thenext 40 days, performance of mice deteriorated significantly, whereasthe performance of MPCs-mix treated mice show a significant better motorfunction as indicated by the balancing ability on the rotorod (A). Micetreated with MPCs-mix demonstrate 50% reduction in motor activity eightdays after mice treated with saline/Data shown for female mice (B). Malemice data are not shown (p<0.05, n=12).

FIGS. 8A-8B illustrate that MPCs-mix transplantation extend the survivalof SOD1 transgenic mice. Comparison of survival of SOD1 transgenic micetreated with saline/MPCs-GFP/MPCs-GDNF or MPC-mix. (A) Kaplan-Meiergraph demonstrates that the cumulative survival of MPCs-mix treated SOD1mice (n=17) is prolonged compared with saline (n=12)/MPCs-GFP (n=12) orMPCs-GDNF treaded SOD1mice (n=12). (B) There is a significantprolongation of the average life span by 10-13 days in the MPCs-mixtreated group compared with the three other groups (*p<0.05).

FIGS. 9A-9B are graphs illustrating that the transplantation of mouseMPC-mix delayed the onset of symptoms in SOD1 mice. Mouse MPC-mix wereinjected on day 90, 104, 118 age into SOD1 mice (n=8, C57b1 background).(A) Rotarod performance (P<0.01 as determined by repeated measurements).(B) The percent of mice that are free of symptoms (20% reduction onrotarod).

FIG. 10 is a bar graph illustrating that MPC-mix conditioned mediasynergistically increases akt phosphorylation in motor neuron cell lineunder hypoxic conditions. Conditioned media from various MPC clones wereadded to NSC-34 cells for 24 hours in hypoxic environment. The ratio ofAKT vs. phosphorylated-AKT proteins was analyzed on Western blot usingspecific antibody.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

The present invention, in some embodiments thereof, relates to musclecells which have been genetically modified to express neurotrophicfactors (NTFs) and uses thereof.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not necessarily limited in itsapplication to the details set forth in the following description orexemplified by the Examples. The invention is capable of otherembodiments or of being practiced or carried out in various ways.

The present inventors uncovered that simultaneously up-regulating fourneurotrophic factors in muscle cells had a synergistically greatertherapeutic effect when compared with the up-regulation of oneneurotrophic factor as tested in mouse models for motor neuronpathologies.

The present inventors propose the generation of muscle cells populationscomprising 4 subpopulations, each being genetically modified to expressa different neurotrophic factor. By mixing the different sub-populationsin alternate ratios, the present inventors propose the generation ofcell populations tailored for the treatment of particular nerve and/ormuscle disorders.

As well as genetic modification of the polynucleated muscle fibersthemselves, the present inventors propose the genetic modification ofmononucleated muscle precursors for this purpose. For example, a veryslow adherent cell population of adult skeletal muscle cells haspreviously been isolated Sarig et at, [Stem Cells 2006; 24: 1769-1778],which could be propagated in suspension as unattached clusters,consisting of pure populations of muscle progenitor cells (MPCs). Thesecells were shown be MyoD positive and CD34 and CD45 negative. Usingthese cells, the present inventors produced genetically manipulatedmuscle progenitor cells (MPCs) as a vehicle to facilitate expression ofthe genes encoding neurotrophic factors (NTFs); BDNF, GDNF, IGF-1 andVEGF via the generation of 4 distinct subpopulations.

These genetically manipulated MPCs (referred to herein as MPCs-NTFs orMPC-mix) were shown to be useful for the treatment of motor neuronpathology in two animal models. In the rat model of sciatic nerve crush,the animals showed improved motorod performance (FIG. 3), an improvedcompound muscle action potential (CMAP; FIG. 4) and increasedpreservation of the innervated neuromuscular junction (NMJ; FIGS. 5A-B))following transplantation of the genetically modified MPCs as comparedto control animals. In SOD1^(G) mice, a model for ALS, the animalsshowed a delay in reduction of motor function (FIGS. 7A-B and 9A-B) anda prolonged lifespan (FIGS. 8A-B).

Thus, according to one aspect of the present invention, there isprovided an isolated muscle progenitor cell genetically modified toexpress at least one neurotrophic factor.

The muscle progenitor cells of this aspect of the present invention mayexpress myogenic proteins including, but not limited the intermediatefilament protein desmin, MyoD, Myf-5 and Pax-7.

According to a particular embodiment, the muscle progenitor cells areMyoD positive, CD34 negative and CD45 negative.

Ex vivo and in vitro cell populations useful as a source of cells mayinclude fresh or frozen cell populations obtained from embryonic, fetal,pediatric or adult tissue. The progenitor cells may be obtained from anymammalian species, e.g. human, equine, bovine, porcine, canine, feline,rodent, e.g. mice, rats, hamster, primate, etc.

According to a particular embodiment, the muscle progenitor cells arederived from adult tissue.

Methods of obtaining skeletal muscle progenitor cells are known in theart—see for example Sarig et al [Stem Cells 2006; 24: 1769-1778], thecontents of which are incorporated herein by reference.

Primary skeletal muscles cells may be obtained from subjects during abiopsy or surgical procedure. The biopsy can be obtained by using abiopsy needle under a local anesthetic, which makes the procedure quickand simple. The small biopsy core of the isolated tissue can then beexpanded and cultured to obtain the tissue cells.

Methods for the isolation and culture of cells are discussed byFreshney, Culture of Animal Cells. A Manual of Basic Technique, 2d Ed.,A. R. Liss, Inc., New York, 1987, Ch. 9, pp. 107-126. Cells may beisolated using techniques known to those skilled in the art. Forexample, the tissue can be cut into pieces, disaggregated mechanicallyand/or treated with digestive enzymes and/or chelating agents thatweaken the connections between neighboring cells making it possible todisperse the tissue into a suspension of individual cells withoutappreciable cell breakage. If necessary, enzymatic dissociation can beaccomplished by mincing the tissue and treating the minced tissue withany of a number of digestive enzymes either alone or in combination.These include but are not limited to trypsin, chymotrypsin, collagenase,elastase, and/or hyaluronidase, DNase, pronase, and dispase. Mechanicaldisruption can also be accomplished by a number of methods including,but not limited to, scraping the surface of the tissue, the use ofgrinders, blenders, sieves, homogenizers, pressure cells, or insonatorsto name but a few.

The cells are then suspended in a proliferation medium. Typically, sucha medium may comprise an antibiotic and additional components which aidin the proliferation of the muscle progenitor cells—such factors mayinclude for example fetal calf serum, steroids, basic fibroblast growthfactor, insulin and glutamine.

According to one embodiment, the heterogeneous cell population obtainedfrom tiypsinized skeletal muscle is pre-plated in untreated (e.g.plastic) cell culture plates. After the adherence of the “fibroblastic”cells, the unattached cells are collected and plated ingelatin/poly-lysine/collagen-coated plates to enable the adherence ofthe majority of muscle progenitor cells.

According to one embodiment, after at least one day, the non-adherentcells of the gelatin culture are collected and maintained by serialpassages either as suspended myospheres or as adherent cultures. Thisresults in a population of cells comprising muscle progenitor cellswhich are MyoD positive, CD34 negative and CD45 negative.

Cells which are CD34 negative and CD45 negative may be selected usingvarious methods known in the art including fluorescent activated cellsorting (FACS). Alternatively or in addition, magnetic cell sorting(MACS) or immunopanning may be employed to sort the cells.

The above described cell populations are genetically modified to expressat least one neurotrophic factor.

As used herein, the phrase “neurotrophic factor” refers to a cell factorthat acts on the cerebral nervous system comprising growth,differentiation, functional maintenance and/or survival effects onneurons.

Examples of neurotrophic factors include, but are not limited to, glialderived neurotrophic factor (GDNF), GenBank accession Nos. L19063/L15306(SEQ ID NO: 1) and AAA67910 (SEQ ID NO: 2); nerve growth factor (NGF),GenBank accession Nos. X53655 (SEQ ID NO: 3) CAA37703 (SEQ ID NO: 4);brain-derived neurotrophic factor (BDNF), GenBank accession Nos. X91251(SEQ ID NO: 5) and CAA62632 (SEQ ID NO: 6); neurotrophin-3 (NT-3),GenBank Accession Nos. M37763 (SEQ ID NO: 7) and AAA59953 (SEQ ID NO:8); neurotrophin-4/5; Neurturin (NTN), GenBank Accession Nos. NM_004558(SEQ ID NO: 9) and NP_004549 (SEQ ID NO: 10); Neurotrophin-4, GenBankAccession Nos. M86528 (SEQ ID NO: 11) and AAA60154 (SEQ ID NO: 12);Persephin, GenBank accession Nos. AF040962 (SEQ ID NO: 13) and AAC39640(SEQ ID NO: 14); artemin (ART), GenBank accession Nos. AF115765 (SEQ IDNO: 15) and AAD13110 (SEQ ID NO: 16); ciliary neurotrophic factor(CNTF), GenBank accession Nos. NM_000614 (SEQ ID NO: 17) and NP_000605(SEQ ID NO: 18); insulin growth factor-I (IGF-1), GenBank accession Nos.NM_000618 (SEQ ID NO: 19) and NP_000609 (SEQ ID NO: 20); and NeublastinGenBank accession Nos. AF120274 (SEQ ID NO: 21) and AAD21075 (SEQ ID NO:22).

A neurotrophic factor of the present invention also refers to homologs(e.g., polypeptides which are at least 50%, at least 55%, at least 60%,at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, atleast 87%, at least 89%, at least 91%, at least 93%, at least 95% ormore say 100% homologous to the above mentioned sequences as determinedusing BlastP software of the National Center of BiotechnologyInformation (NCBI) using default parameters). The homolog may also referto a deletion, insertion, or substitution variant, including an aminoacid substitution, thereof and biologically active polypeptide fragmentsthereof.

To express the neurotrophic factors in the muscle progenitor cellsdescribed herein, polynucleotides which encode the factors are ligatedinto a nucleic acid construct suitable for muscle cell expression. Sucha nucleic acid construct includes a promoter sequence for directingtranscription of the polynucleotide sequence in the cell in aconstitutive or inducible manner.

Constitutive promoters suitable for use with some embodiments of theinvention are promoter sequences which are active under mostenvironmental conditions and most types of cells such as thecytomegalovirus (CMV) and Rous sarcoma virus (RSV). Inducible promoterssuitable for use with some embodiments of the invention include forexample tetracycline-inducible promoter (Zabala M, et al., Cancer Res.2004, 64(8): 2799-804).

Eukaryotic promoters typically contain two types of recognitionsequences, the TATA box and upstream promoter elements. The TATA box,located 25-30 base pairs upstream of the transcription initiation site,is thought to be involved in directing RNA polymerase to begin RNAsynthesis. The other upstream promoter elements determine the rate atwhich transcription is initiated.

As mentioned, the promoter utilized by the nucleic acid construct ofsome embodiments of the invention is active in the specific cellpopulation transformed—i.e. muscle progenitor cells and morespecifically in mature muscle cells. Examples of such promoters includethe myosin, actin or skeletal muscle creatine kinase (CK) promoter.

Enhancer elements can stimulate transcription up to 1,000 fold fromlinked homologous or heterologous promoters. Enhancers are active whenplaced downstream or upstream from the transcription initiation site.Many enhancer elements derived from viruses have a broad host range andare active in a variety of tissues. For example, the SV40 early geneenhancer is suitable for many cell types. Other enhancer/promotercombinations that are suitable for some embodiments of the inventioninclude those derived from polyoma virus, human or murinecytomegalovirus (CMV), the long term repeat from various retrovirusessuch as murine leukemia virus, murine or Rous sarcoma virus and HIV.See, Enhancers and Eukaryotic Expression, Cold Spring Harbor Press, ColdSpring Harbor, N.Y. 1983, which is incorporated herein by reference.

In the construction of the expression vector, the promoter is preferablypositioned approximately the same distance from the heterologoustranscription start site as it is from the transcription start site inits natural setting. As is known in the art, however, some variation inthis distance can be accommodated without loss of promoter function.

In addition to the elements already described, the expression vector ofsome embodiments of the invention may typically contain otherspecialized elements intended to increase the level of expression ofcloned nucleic acids or to facilitate the identification of cells thatcarry the recombinant DNA. For example, a number of animal virusescontain DNA sequences that promote the extra chromosomal replication ofthe viral genome in permissive cell types. Plasmids bearing these viralreplicons are replicated episomally as long as the appropriate factorsare provided by genes either carried on the plasmid or with the genomeof the host cell.

The vector may or may not include a eukaryotic replicon. If a eukaryoticreplicon is present, then the vector is amplifiable in eukaryotic cellsusing the appropriate selectable marker. If the vector does not comprisea eukaryotic replicon, no episomal amplification is possible. Instead,the recombinant DNA integrates into the genome of the engineered cell,where the promoter directs expression of the desired nucleic acid.

Examples for mammalian expression vectors include, but are not limitedto, pcDNA3, pcDNA3.1(+/−), pGL3, pZeoSV2(+/−), pSecTag2, pDisplay,pEF/myc/cyto, pCMV/myc/cyto, pCR3.1, pSinRep5, DH26S, DHBB, pNMT1,pNMT41, pNMT81, which are available from Invitrogen, pCI which isavailable from Promega, pMbac, pPbac, pBK-RSV and pBK-CMV which areavailable from Strategene, pTRES which is available from Clontech, andtheir derivatives.

Expression vectors containing regulatory elements from eukaryoticviruses such as retroviruses can be also used. SV40 vectors includepSVT7 and pMT2. Vectors derived from bovine papilloma virus includepBV-1MTHA, and vectors derived from Epstein Bar virus include pHEBO, andp2O5. Other exemplary vectors include pMSG, pAV009/A⁺, pMTO10/A⁺,pMAMneo-5, baculovirus pDSVE, and any other vector allowing expressionof proteins under the direction of the SV-40 early promoter, SV-40 laterpromoter, metallothionein promoter, murine mammary tumor virus promoter,Rous sarcoma virus promoter, polyhedrin promoter, or other promotersshown effective for expression in eukaryotic cells.

As described above, viruses are very specialized infectious agents thathave evolved, in many cases, to elude host defense mechanisms.Typically, viruses infect and propagate in specific cell types. Thetargeting specificity of viral vectors utilizes its natural specificityto specifically target predetermined cell types and thereby introduce arecombinant gene into the infected cell. Thus, the type of vector usedby some embodiments of the invention will depend on the cell typetransformed. The ability to select suitable vectors according to thecell type transformed is well within the capabilities of the ordinaryskilled artisan and as such no general description of selectionconsideration is provided herein. For example, bone marrow cells can betargeted using the human T cell leukemia virus type I (HTLV-I) andkidney cells may be targeted using the heterologous promoter present inthe baculovirus Autographa californica nucleopolyhedrovirus (AcMNPV) asdescribed in Liang C Y et al., 2004 (Arch Virol. 149: 51-60).

According to one embodiment, a lentiviral vector is used to transfectthe muscle cells.

Various methods can be used to introduce the expression vector of someembodiments of the invention into muscle cells. Such methods aregenerally described in Sambrook et al., Molecular Cloning: A LaboratoryManual, Cold Springs Harbor Laboratory, New York (1989, 1992), inAusubel et al., Current Protocols in Molecular Biology, John Wiley andSons, Baltimore, Md. (1989), Chang et al., Somatic Gene Therapy, CRCPress, Ann Arbor, Mich. (1995), Vega et al., Gene Targeting, CRC Press,Ann Arbor Mich. (1995), Vectors: A Survey of Molecular Cloning Vectorsand Their Uses, Butterworths, Boston Mass. (1988) and Gilboa et al.[Biotechniques 4 (6): 504-512, 1986] and include, for example, stable ortransient transfection, lipofection, electroporation and infection withrecombinant viral vectors. In addition, see U.S. Pat. Nos. 5,464,764 and5,487,992 for positive-negative selection methods.

Introduction of nucleic acids by viral infection offers severaladvantages over other methods such as lipofection and electroporation,since higher transfection efficiency can be obtained due to theinfectious nature of viruses.

Other vectors can be used that are non-viral, such as cationic lipids,polylysine, and dendrimers. Nanoparticles are also contemplated.

Other modes of transfection that do not involve integration include theuse of minicircle DNA vectors or the use of PiggyBac transposon thatallows the transfection of genes that can be later removed from thegenome.

The muscle progenitor cells may be genetically modified to express asingle neurotrophic factor, to co-express two neurotrophic factors,three neurotrophic factors, four neurotrophic factors or even moreneurotrophic factors.

Thus muscle progenitor cells genetically modified to express at leastone of GDNF, VEGF, BDNF and IGF-1 are contemplated.

Further, muscle progenitor cells genetically modified to express atleast two of GDNF, VEGF, BDNF and IGF-1 are contemplated.

In addition, muscle progenitor cells genetically modified to express atleast three of GDNF, VEGF, BDNF and IGF-1 are contemplated.

Further, muscle progenitor cells genetically modified to express each ofGDNF, VEGF, BDNF and IGF-1 are also contemplated.

It will be appreciated that various construct schemes can be utilized toexpress more than one neurotrophic factor from a single nucleic acidconstruct.

For example, two neurotrophic factors can be co-transcribed as apolycistronic message from a single promoter sequence of the nucleicacid construct. To enable co-translation of both neurotrophic factorsfrom a single polycistronic message, the first and second polynucleotidesegments can be transcriptionally fused via a linker sequence includingan internal ribosome entry site (TRES) sequence which enables thetranslation of the polynucleotide segment downstream of the IRESsequence. In this case, a transcribed polycistronic RNA moleculeincluding the coding sequences of both the first and the secondneurotrophic factors will be translated from both the capped 5′ end andthe internal IRES sequence of the polycistronic RNA molecule to therebyproduce both the first and the second neurotrophic factors.

Alternatively, the first and second polynucleotide segments can betranslationally fused via a protease recognition site cleavable by aprotease expressed by the cell to be transformed with the nucleic acidconstruct. In this case, a chimeric polypeptide translated will becleaved by the cell expressed protease to thereby generate both thefirst and the second neurotrophic factors.

Still alternatively, the nucleic acid construct of some embodiments ofthe invention can include two promoter sequences each being forseparately expressing a specific neurotrophic factor of the neurotrophicfactors described above. These two promoters which can identical ordistinct can be constitutive, tissue specific or regulatable (e.g.inducible) promoters functional in one or more cell types.

It will be appreciated that the present invention also contemplatesgenetically modifying muscle progenitor cells to express a singleneurotrophic factor which are then mixed with a second population ofmuscle progenitor cells which are genetically modified to express anon-identical neurotrophic factor.

Thus, according to another aspect of the present invention there isprovided an isolated cell population, comprising at least foursubpopulations of muscle cells, each of the at least four subpopulationbeing distinct in that they are genetically modified to express adifferent neurotrophic factor, wherein the neurotrophic factor isselected from the group consisting of glial derived neurotrophic factor(GDNF), insulin growth factor (IGF-1), vascular endothelial growthfactor (VEGF) and brain-derived neurotrophic factor (BDNF).

The term “muscle cell” as used herein refers to any cell thatcontributes to muscle tissue. Myoblasts, satellite cells, myotubes,myofibers, and myofibril tissues are all included in the term “musclecells”. The muscle cell may be comprised within skeletal, cardiac andsmooth muscles, particularly within skeletal muscle.

According to a particular embodiment, the muscle cell is a skeletalmuscle progenitor cell.

By mixing the subpopulations in different amounts, it is possible tocontrol the ratio of neurotrophic factors in the cell population.

The percentage of cells that express a particular neurotrophic factormay be selected according to the disease for which the cells areintended to treat.

Certain neurotrophic factors or set of neurotrophic factors have beenshown to be particularly beneficial for treating a particular disease.For example, cells of the present invention which secrete NT3, IGF1 andBDNF may be particularly suitable for treating ALS.

The present inventors have shown that cell populations which comprisesimilar amount of cells genetically modified to express one of GDNF,BDNF, VEG-F and IGF-1 (i.e. a mixture of four different cellsub-populations—i.e. MPC-mix, the first genetically modifiedsub-population to express GDNF, the second genetically modifiedsub-population to express BDNF, the third genetically modifiedsub-population to express VEG-F and the fourth genetically modifiedsub-population to express IGF-1, where each population is present insimilar amounts) show improved therapeutic properties (synergism) whencompared with cell populations which comprise only one of these celltypes for the treatment of ALS and sciatic nerve crush.

The cell populations described herein can be used to treat additionalnerve diseases, disorders damage or injury.

The injury or disease may be associated with motor neurons and/orsensory neurons.

According to a particular embodiment, the nerve disease is aneuromuscular disease (spinal muscular atrophy, a amyotrophic lateralsclerosis (ALS), a Werdnig Hoffman disease, a Charcot-Marie toothdisease, multiple sclerosis, myasthenia gravis, muscular dystrophy and amyositis).

According to another embodiment, the nerve disease is a motor neurondisease (e.g. amyotrophic lateral sclerosis (ALS), primary lateralsclerosis (PLS), pseudobulbar palsy and progressive bulbar palsy).

Contemplated nerve damage which may be aided using the cell populationsdescribed herein include peripheral nerve injury, peripheral nerveinflammation, autonomic nerve injury, pelvic nerve damage, burn, blunttrauma, back injury, back pain, or sciatica.

Since sensory neurons may also be affected by the neurtotrophic factorsdescribed herein, the present invention also contemplates treating pain.The pain may be associated with nerve damage or from other sources—e.g.the pain may be due to a disease such as cancer.

The cells of the present invention can be administered to the treatedindividual using a variety of transplantation approaches, the nature ofwhich depends on the site of implantation. According to one embodiment,the site of implantation is the muscle.

The term or phrase “transplantation”, “cell replacement” or “grafting”are used interchangeably herein and refer to the introduction of thecells of the present invention to target tissue. The cells can bederived from the recipient or from an allogeneic or xenogeneic donor.

For transplanting, the cell suspension is drawn up into the syringe andadministered to transplantation recipients. Multiple injections may bemade using this procedure.

Typically, the method of the present invention does not requireimmunosuppression. However, if required, the present inventioncontemplates encapsulating the muscle cells or administration ofimmunosuppressive agents.

It will be appreciated that as well as cell therapy for delivery ofneurotrophic factors, the present invention also contemplates genetherapy for the transfer of neurotrophic factors such as described byWang et al., The Journal of Neuroscience, 2002, 22(16):6920-6928; andAcsadi et al., Human Gene Therapy 13:1047-1059,2002, the contents ofboth being incorporated herein by reference.

Gene therapy as used herein refers to the transfer of genetic material(e.g. DNA or RNA) of interest into a host to treat or prevent a geneticor acquired disease or condition or phenotype. The genetic material ofinterest encodes a product (e.g. a protein, polypeptide, peptide,functional RNA, antisense) whose production in vivo is desired. Forexample, the genetic material of interest can encode a neurotrophicfactor. For review see, in general, the text “Gene Therapy” (Advanced inPharmacology 40, Academic Press, 1997).

In in vivo gene therapy, target cells are not removed from the subjectrather the genetic material to be transferred is introduced into thecells of the recipient organism in situ, that is within the recipient.These genetically altered cells have been shown to express thetransfected genetic material in situ.

To confer specificity, preferably the nucleic acid constructs used toexpress the polypeptides of the present invention comprise musclecell-specific promoter sequence elements, as described herein above.

Introduction of nucleic acids by infection in both in vivo therapyoffers several advantages over the other listed methods. Higherefficiency can be obtained due to their infectious nature. Moreover,viruses are very specialized and typically infect and propagate inspecific cell types. Thus, their natural specificity can be used totarget the vectors to specific cell types in vivo or within a tissue ormixed culture of cells. Viral vectors can also be modified with specificreceptors or ligands to alter target specificity through receptormediated events.

In addition, recombinant viral vectors are useful for in vivo expressionof a desired nucleic acid because they offer advantages such as lateralinfection and targeting specificity. Lateral infection is inherent inthe life cycle of, for example, retrovirus and is the process by which asingle infected cell produces many progeny virions that bud off andinfect neighboring cells. The result is that a large area becomesrapidly infected, most of which was not initially infected by theoriginal viral particles. This is in contrast to vertical-type ofinfection in which the infectious agent spreads only through daughterprogeny. Viral vectors can also be produced that are unable to spreadlaterally. This characteristic can be useful if the desired purpose isto introduce a specified gene into only a localized number of targetedcells.

Retroviral vectors can be constructed to function either as infectiousparticles or to undergo only a single initial round of infection. In theformer case, the genome of the virus is modified so that it maintainsall the necessary genes, regulatory sequences and packaging signals tosynthesize new viral proteins and RNA. Once these molecules aresynthesized, the host cell packages the RNA into new viral particleswhich are capable of undergoing further rounds of infection. Thevector's genome is also engineered to encode and express the desiredrecombinant gene. In the case of non-infectious viral vectors, thevector genome is usually mutated to destroy the viral packaging signalthat is required to encapsulate the RNA into viral particles. Withoutsuch a signal, any particles that are formed will not contain a genomeand therefore cannot proceed through subsequent rounds of infection. Thespecific type of vector will depend upon the intended application. Theactual vectors are also known and readily available within the art orcan be constructed by one skilled in the art using well-knownmethodology.

Since transduction of cells with conditionally replicating adenoviralvectors is significantly more effective in target cell lysis and spreadof viral infection, the nucleic acid construct can include aconditionally replicating adenovirus.

The viral vectors, containing the endothelial cell specific promoters,can also be used in combination with other approaches to enhancetargeting of the viral vectors. Such approaches include short peptideligands and/or bispecific or bifunctional molecule or diabodies(Nettelbeck et al. Molecular Therapy 3:882; 2001).

According to a particular embodiment, the gene therapy is effected suchthat the gene is not integrated into the genome of the cell. Thus, forexample the use of liposomes for the delivery of the neurotrophicfactors is also contemplated by the present inventors.

In any of the methods described herein, the cells or the constructs canbe administered either per se or, preferably as a part of apharmaceutical composition that further comprises a pharmaceuticallyacceptable carrier.

As used herein a “pharmaceutical composition” refers to a preparation ofone or more of the chemical conjugates described herein, with otherchemical components such as pharmaceutically suitable carriers andexcipients. The purpose of a pharmaceutical composition is to facilitateadministration of a compound to a subject.

Hereinafter, the term “pharmaceutically acceptable carrier” refers to acarrier or a diluent that does not cause significant irritation to asubject and does not abrogate the biological activity and properties ofthe administered compound. Examples, without limitations, of carriersare propylene glycol, saline, emulsions and mixtures of organic solventswith water.

Herein the term “excipient” refers to an inert substance added to apharmaceutical composition to further facilitate administration of acompound. Examples, without limitation, of excipients include calciumcarbonate, calcium phosphate, various sugars and types of starch,cellulose derivatives, gelatin, vegetable oils and polyethylene glycols.

According to a preferred embodiment of the present invention, thepharmaceutical carrier is an aqueous solution of saline.

Techniques for formulation and administration of drugs may be found in“Remington's Pharmaceutical Sciences,” Mack Publishing Co., Easton, Pa.,latest edition, which is incorporated herein by reference.

Suitable routes of administration include direct administration into thetissue or organ of interest.

For any preparation used in the methods of the invention, thetherapeutically effective amount or dose can be estimated initially fromin vitro and cell culture assays. Preferably, a dose is formulated in ananimal model to achieve a desired concentration or titer. Suchinformation can be used to more accurately determine useful doses inhumans.

Toxicity and therapeutic efficacy of the active ingredients describedherein can be determined by standard pharmaceutical procedures in vitro,in cell cultures or experimental animals.

For example, transgenic mice may be used as a model for ALS diseasewhich comprise SOD-1 mutations.

Survival and rotational behavior (e.g. on a rotarod) of the animals maybe analyzed (as in Examples 2 and 3) following administration of thecells of the present invention.

The data obtained from these in vitro and cell culture assays and animalstudies can be used in formulating a range of dosage for use in human.The dosage may vary depending upon the dosage form employed and theroute of administration utilized. The exact formulation, route ofadministration and dosage can be chosen by the individual physician inview of the patient's condition, (see e.g., Fingl, et al., 1975, in “ThePharmacological Basis of Therapeutics”, Ch. 1 p. 1).

For injection, the active ingredients of the pharmaceutical compositionmay be formulated in aqueous solutions, preferably in physiologicallycompatible buffers such as Hank's solution, Ringer's solution, orphysiological salt buffer.

Dosage amount and interval may be adjusted individually to levels of theactive ingredient which are sufficient to effectively regulate theneurotransmitter synthesis by the implanted cells. Dosages necessary toachieve the desired effect will depend on individual characteristics androute of administration. Detection assays can be used to determineplasma concentrations.

Depending on the severity and responsiveness of the condition to betreated, dosing can be of a single or a plurality of administrations,with course of treatment lasting from several days to several weeks ordiminution of the disease state is achieved.

The amount of a composition to be administered will, of course, bedependent on the individual being treated, the severity of theaffliction, the manner of administration, the judgment of theprescribing physician, etc. The dosage and timing of administration willbe responsive to a careful and continuous monitoring of the individualchanging condition. For example, a treated ALS's patient will beadministered with an amount of cells which is sufficient to alleviatethe symptoms of the disease, based on the monitoring indications.

As used herein the term “about” refers to ±10%

The terms “comprises”, “comprising”, “includes”, “including”, “having”and their conjugates mean “including but not limited to”.

The term “consisting of” means “including and limited to”.

The term “consisting essentially of” means that the composition, methodor structure may include additional ingredients, steps and/or parts, butonly if the additional ingredients, steps and/or parts do not materiallyalter the basic and novel characteristics of the claimed composition,method or structure.

As used herein, the singular form “a”, “an” and “the” include pluralreferences unless the context clearly dictates otherwise. For example,the term “a compound” or “at least one compound” may include a pluralityof compounds, including mixtures thereof.

As used herein the term “method” refers to manners, means, techniquesand procedures for accomplishing a given task including, but not limitedto, those manners, means, techniques and procedures either known to, orreadily developed from known manners, means, techniques and proceduresby practitioners of the chemical, pharmacological, biological,biochemical and medical arts.

As used herein, the term “treating” includes abrogating, substantiallyinhibiting, slowing or reversing the progression of a condition,substantially ameliorating clinical or aesthetical symptoms of acondition or substantially preventing the appearance of clinical oraesthetical symptoms of a condition.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination or as suitable in any other describedembodiment of the invention. Certain features described in the contextof various embodiments are not to be considered essential features ofthose embodiments, unless the embodiment is inoperative without thoseelements.

Various embodiments and aspects of the present invention as delineatedhereinabove and as claimed in the claims section below find experimentalsupport in the following examples.

EXAMPLES

Reference is now made to the following examples, which together with theabove descriptions illustrate some embodiments of the invention in a nonlimiting fashion.

Generally, the nomenclature used herein and the laboratory proceduresutilized in the present invention include molecular, biochemical,microbiological and recombinant DNA techniques. Such techniques arethoroughly explained in the literature. See, for example, “MolecularCloning: A laboratory Manual” Sambrook et al., (1989); “CurrentProtocols in Molecular Biology” Volumes I-III Ausubel, R. M., ed.(1994); Ausubel et al., “Current Protocols in Molecular Biology”, JohnWiley and Sons, Baltimore, Md. (1989); Perbal, “A Practical Guide toMolecular Cloning”, John Wiley & Sons, New York (1988); Watson et al.,“Recombinant DNA”, Scientific American Books, New York; Birren et al.(eds) “Genome Analysis: A Laboratory Manual Series”, Vols. 1-4, ColdSpring Harbor Laboratory Press, New York (1998); methodologies as setforth in U.S. Pat. Nos. 4,666,828; 4,683,202; 4,801,531; 5,192,659 and5,272,057; “Cell Biology: A Laboratory Handbook”, Volumes I-III Cellis,J. E., ed. (1994); “Culture of Animal Cells—A Manual of Basic Technique”by Freshney, Wiley-Liss, N.Y. (1994), Third Edition; “Current Protocolsin Immunology” Volumes I-III Coligan J. E., ed. (1994); Stites et al.(eds), “Basic and Clinical Immunology” (8th Edition), Appleton & Lange,Norwalk, Conn. (1994); Mishell and Shiigi (eds), “Selected Methods inCellular Immunology”, W. H. Freeman and Co., New York (1980); availableimmunoassays are extensively described in the patent and scientificliterature, see, for example, U.S. Pat. Nos. 3,791,932; 3,839,153;3,850,752; 3,850,578; 3,853,987; 3,867,517; 3,879,262; 3,901,654;3,935,074; 3,984,533; 3,996,345; 4,034,074; 4,098,876; 4,879,219;5,011,771 and 5,281,521; “Oligonucleotide Synthesis” Gait, M. J., ed.(1984); “Nucleic Acid Hybridization” Hames, B. D., and Higgins S. J.,eds. (1985); “Transcription and Translation” Hames, B. D., and HigginsS. J., eds. (1984); “Animal Cell Culture” Freshney, R. I., ed. (1986);“Immobilized Cells and Enzymes” IRL Press, (1986); “A Practical Guide toMolecular Cloning” Perbal, B., (1984) and “Methods in Enzymology” Vol.1-317, Academic Press; “PCR Protocols: A Guide To Methods AndApplications”, Academic Press, San Diego, Calif. (1990); Marshak et al.,“Strategies for Protein Purification and Characterization—A LaboratoryCourse Manual” CSHL Press (1996); all of which are incorporated byreference as if fully set forth herein. Other general references areprovided throughout this document. The procedures therein are believedto be well known in the art and are provided for the convenience of thereader. All the information contained therein is incorporated herein byreference.

GENERAL MATERIALS AND METHODS

Protocol for neurotrophic factors secreting muscle progenitor cellspreparation: Rat and mouse MPCs were used as a vehicle to introducevectors expressing growth factors. The MPCs were propagated in a growthmedium containing Dulbecco's modified Eagle's medium (DMEM) supplementedwith 100 mg/ml streptomycin, 100 U/ml penicillin, 12.5 units/ml nystatin(SPN, Biological Industries, Beit Haemek, Israel), 2 mML-glutamine(Biological Industries), and 10% fetal calf serum (BiologicalIndustries).

The constructs of the neurotrophic genes were generated using ViraPower™Promoterless Lentiviral Gateway® Kit (Invitrogen, Carlsbad, Calif.,USA). The human GDNF, VEGF, IGF-1 and BDNF genes were amplified from thepBluescript plasmids that were purchased from Harvard Institute ofProteomics, Boston, USA, using Plasmid Midi Kit (Qiagen, Valencia, USA).Each of the four genes was inserted into the virus under the CMVpromoter in a recombination reaction. For each reaction sample a plasmidcontaining the CMV promoter was incubated over-night at room temperaturewith a plasmid containing the DNA, a destination plasmid and therecombination enzyme-LR clonase (Invitrogen). Following establishment ofthe constructs, they were transformed into One Shot™ Stb13™ Competent E.coli (Invitrogen). 4 μl of the recombination reaction were added to OneShot™ Stb13™ Competent E. coli and were incubated for 30 minutes on ice.After incubation the mix was transferred to 42° C. for 30 seconds andfrom there to 2 minutes on ice. 250 μl of SOC medium was added to themix and incubated at 37° C. After one hour, the mix was placed on LBagar plates with ampicillin (Sigma-Aldrich, St. Louis, Mo., USA) for 24hours at 37° C. On the following day, one colony was picked and DNA wasproduced using midi kit. For each transfection sample, 4 μg DNA (of eachgene separately) were diluted in 1.5 ml Opti-MEM (Biologicalindustries). Lipofectamaine 2000 (Invitrogen) was diluted in 1.5 mlOpti-MEM. After 5 minutes of room temperature incubation, the dilutedmix and DNA with the diluted Lipofectamine 2000 were combined andincubated for 20 minutes in room temperature. After incubation, the 3 mlof complexes were added to flasks containing 95% confluent MPCs culturedin an antibiotic free medium and incubated at 37° C. in a CO₂ incubator.Six hours later, the cells' media was replaced with their regular growthmedium. On the next day, 4 mg/ml of Blastocidin was added to the cellsfor selection for two weeks.

Immunocytochemistry of muscle progenitor cells: Cells grown oncoverslips were fixed with 4% paraformaldehyde for 10 minutes, washedwith phosphate-buffered saline (PBS), and then incubated in a blockingand permeabilization solution (5% normal goat serum, 1% bovine serumalbumin, and 0.5% Triton X-100 in PBS) and incubated with a primaryantibody overnight at 4° C. After being washed with PBS, cells wereincubated with an Alexa-conjugated secondary antibody. The nuclei werecounterstained with 4,6-diamidino-2-phenylindole (DAPI; 1:500;Sigma-Aldrich). The following primary antibodies were used: rabbitα-BDNF (1:100; Santa Cruz Biotechnology Inc., Santa Cruz, Calif., USA),rabbit α-GDNF (1:100; Santa Cruz Biotechnology), mouse α-IGF-1 (1:100;Santa Cruz Biotechnology), and mouse α-VEGF (1:100; Santa CruzBiotechnology). Secondary antibodies were Alexa Fluor 488 (1:500;Invitrogen) and Alexa Fluor 568 (1:500; Invitrogen). The quantificationof positive cells was performed on five random fields photographed at amagnification of X100, as a percentage of the positive cells from thenumber of total DAPI-positive nuclei.

ELISA analysis: Cell supernatant pre- and post-transfection wascollected, frozen, and quantified. An enzyme-linked immunosorbent assay(ELISA) kit (R&D systems, Minneapolis, Minn., USA) was used to detectthe presence of each one of the secreted neurotrophic factors. The assaywas conducted according to the manufacturer's protocol in triplicate,and results were read at wavelengths of 450/550 using an ELISA reader(Powerwave X; Biotek Instruments, Winooski, Vt., USA). Results werecompared between the cells' media before and after transfection.

Cell viability assay: The MPCs conditioned media was tested for itsability to protect motor neurons cell-line (NSCs-34) from hypoxicstress. NSCs-34 were placed in hypoxic environment for 48 hours togetherwith the conditioned media of each of the cloned MPCs expressing one ofthe four NTFs, combination of MPCs-NTF, MPCs-GFP, MPCs growth media orserum free growth media.

After 48 hours, Alamar blue 10% (AbD serotec, Kidlington, UK) was addedto the cells for 6 hours. The assay was conducted in triplicate, andresults were read at wavelengths of 590 nm using fluostar device.Results were normalized to cells under the same treatments in normoxia.

The sciatic nerve crush model in rats: The sciatic nerve crush model wasapplied on male Wistar rats (Harlan, Jerusalem) weighing 230-250 g. Ratswere placed under 12-hour-light/12-hour-dark conditions and grown inindividually ventilated cages (IVC) with ad libitum access to food andwater. Rats were anesthetized with Chloral hydrate 7 mg/ml(Sigma-Aldrich, St. Louis). The right sciatic nerve was exposed and avessel clamp was applied 10 mm above the first branching of the nerve,for 30 seconds.

One day after surgery, the control group was injected with 100 μl PBSinto the lesion site (n=9). The second control group was injected with10⁶ rMPCs-GFP cells suspended in 100 μL PBS into the lesion site (n=9).Four treatment groups were injected with 10⁶rMPCs-BDNF/rMPCs-GDNF/rMPCs-IGF-1/rMPCs-VEGF cells suspended in 100 μlPBS and the fifth treatment group was injected with a combination of allrMPCs-NTFs cells—25×10⁴ cells from rMPCs-BDNF, rMPCs-GDNF, rMPCs-IGF-1,and rMPCs-VEGF (a total of 10⁶ cells, n=9).

Rat motor function measurements: Rats were examined for motorfunctioning twice a week, one week prior to injury and three weeksfollowing injury. Motor activity was measured by the (San Diegoinstruments, USA) test. In this test, following a brief training period,adult wild-type rats are able to remain balanced on a rotating rod inaccelerated speed, from 0 to 25 RPM for up to 4 minutes. After a sciaticnerve crush, the rat's ability of balancing is damaged and the animalfalls off the rod after shorter periods of time. The machine has a laserbeam that detects the fall [7-8]. The average of three consecutive runsfrom each session on the Rotarod were assessed and the groups'performance was compared.

Electrophysiological study: Compound muscle action potential (CMAP)amplitudes were recorded from the sciatic innervated cranial tibialmuscles following electric stimulation of the sciatic nerve. An activemonopolar needle electrode was placed over the sciatic nerve at thesciatic notch and a supramaximal intensity electric stimulus of 0.1 msduration was applied. An average of ten consecutive runs from eachmeasurement was documented. The CMAP amplitudes were converted to theratios of the measurements taken at the injured side, divided by thoseof the normal side to adjust for the effect of the anesthesia, musclemasses and other physical variations between rats [32-33].

Immunohistochemistry of rat muscle cells: Hind limb muscles of rats wereremoved and frozen in liquid nitrogen, 15 days after transplantation.Muscles were sectioned at 20 μm using a cryostat (Leica CM1850) andplaced on glass slides for staining. The sections were fixed with 4%paraformaldehyde for 30 minutes, washed with phosphate-buffered saline(PBS), and then incubated in a blocking and permeabilization solution(5% normal goat serum, 1% bovine serum albumin, and 0.5% Triton X-100 inPBS) and incubated with a primary antibody overnight at 4° C. Afterbeing washed with PBS, cells were incubated with an Alexa-conjugatedsecondary antibody. The nuclei were counterstained with4,6-diamidino-2-phenylindole (DAPI; 1:500; Sigma-Aldrich). Theantibodies used were the same as described for the muscle progenitorcells.

Assessment of neuromuscular junction innervations: Endplate innervationwas marked by alpha-bungarotoxin and synaptophysin as describedpreviously [34]. Hind limb muscles were dissected and frozen in liquidnitrogen. Muscles were sectioned at 20 μm using a cryostat and placed onglass slides for staining. The sections were fixed with 4% PFA-PBS andlabeled with alpha-bungarotoxin conjugated with fluorescence markerAlexa Fluor 594 (1:1000, Invitrogen, CA, USA) and anti-synaptophysin(rabbit polyclonal, 1:100, Santa Cruz Biotechnology, Santa Cruz, USA)antibodies overnight at 4° c. After washing with PBS, the sections wereincubated with anti-rabbit Alexa Fluor 488-conjugated antibody (1:1,000,Invitrogen) for one hour at room temperature followed by washes, andcovered with cover glasses using aqueous mounting medium (Invitrogen).NMJs were classified into two groups based on the degree of innervationof postsynaptic receptor plaques by nerve terminals [34]. Endplates werescored as “innervated” if there was overlap with the axon terminal, or“denervated” if the end-plate was not associated with an axon [34].

SOD1-G93A transgenic mice model for ALS: The colony of SOD1-G93Atransgenic mice (SOD1 mice) was obtained from the Jackson Laboratory(USA). The mice were bred with SJL mice. Mice were placed under12-hour-light/12-hour-dark conditions and grown in individuallyventilated cages (IVC) with ad libitum access to food and water.

At the age of 90 and 120 days, mMPCs were transplanted into thegastrocnemius medial and lateral muscles (5×10⁵ cells in 25 ul PBS intoeach hindlimb). The control group was injected with 25 μl PBS into thelesion site (n=24, 12 males and 12 females). The second control groupwas injected with 5×10⁵ mMPCs-GFP cells suspended in 25 μL PBS into thelesion site (n=24, 12 males and 12 females). The third group wasinjected with 5×10⁵ mIVIPCs-GDNF suspended in 100 μl PBS and the fourthgroup was injected with a combination of all mMPCs-NTFs cells—1.25×10⁵cells from mMPCs-BDNF, mMPCs-GDNF, mMPCs-IGF-1, and mMPCs-VEGF (a totalof 5×10⁵ cells, n=24, 12 males and 12 females).

Mice motor function measurements by rotorod: Mice were examined formotor functioning once a week, starting from the age of 80 days. Motoractivity was measured by the (San Diego instruments) test. In this test,following a brief training period, adult wild-type mice are able toremain balanced on a rotating rod in accelerated speed, from 0 to 25 RPMfor up to 4 minutes. With time, SOD1 mice weaken, their ability tobalance is damaged and they fall off the rod after shorter periods oftime. The machine has a laser beam that detects the fall [7-8]. Theaverage of three consecutive runs from each session was assessed and thegroups' performance was compared.

Statistical Analysis: The results are expressed as means±SE. The one wayANOVA test was used to compare the three groups. Statisticalcalculations were performed using SPSS, version 13 (SPSS, Chicago, USA).

Example 1 Characterization of Neurotrophic Factor (NTF) TransfectedMuscle Progenitor Cells (MPCs) RESULTS

Using an immunocytochemical study and ELISA analysis, the proteinexpression and secretion of neurotrophic factors was measured followinggene transfection. It was found that 100% of the genetically manipulatedMPCs had a strong positive expression of BDNF, GDNF, IGF-1, and VEGF.The secretion and the presence of BDNF, GDNF, IGF-1, and VEGF in themediaprior to and following transfection was analyzed using ELISA kit.High levels of the four neurotrophic factors were demonstrated comparedwith untransfected MPCs (FIGS. 1A-K).

After 48 hours of culture in an hypoxic environment, the viability ofthe cells of the motor neuron cell-line NSCs-34 decreased. However,cells that were cultured in the MPC-NTF conditioned media were protected(FIGS. 2A-C). Results presented as ratio from normoxic conditions.

Example 2 Rats Improved Motor Function After Cell Transplantation

All rats suffered from a right hind limb limp after crush and theirmotor function deteriorated. All the rat groups performed equally wellon the rotorod prior to the injury. However, immediately following thecrush, the performance of rats markedly declined by 60%. Three dayslater, PBS treated rats demonstrated poor motor function (98.5±4.6seconds on rotorod) while the singly transfected MPCs(GFP/BDNF/GDNF/IGF-1/VEGF) treated rats showed a moderate improvement(125±12.5; 152±9.7; 129±11.2; 129±13.4; 121±9.7, respectively). When amixture of all four NTF transfected MPCs were transplanted, the ratsdemonstrated significant better motor performance (183.8±5.3, p<0.05).The same trend was observed six and eight days after the crush (FIG. 3).

Example 3 Electrophysiology Study Indicates Axonal Regeneration inMPCs-NTFs Treated Rats

Decreased compound muscle action potential (CMAP) was observedimmediately following the sciatic crush in all the groups when comparedto the non-injured contra lateral side. Four days following the surgery,while the average ratio of CMAP, prior to the transplantation andfollowing the transplantation, in the singly transfectedMPCs-(GFP/BDNF/GDNF/IGF-1/VEGF) showed a poor increase in CMAP amplitude(0.2±0.12; 0.26±0.09; 0.12±0.04; 0.32±0.16; 0.26±0.07, respectively), asignificantly improved CMAP ratio of 0.4±0.09 was found in the grouptransplanted with a mixture of all four NTF transfected MPCs (FIG. 4).

Example 4 MPCs-NTFs Inhibited NMJs Denervation

Two weeks following sciatic nerve crush, NMJs were analyzed within thecrush area and the gastocnemios and tibialis muscles. Double stainedendplates, with acetylcholine receptor ligand, alpha bungarotoxin andantibodies against the post synaptic protein, synptophysin, were countedas innervated NMJ. After examining over 100 stained slides, 69%±12preservation of innervated NMJs in the injured gastocnemios and tibialismuscles was observed, as compared to the uninjured hind limb. Incontrast, rats transplanted with a mixture of all four NTF transfectedMPCs showed higher preservation (89%±1.5) of the innervated NMJ comparedto the uninjured limbs (FIGS. 5A-B).

Example 5 MPC Expressing NTF Can Be Detected in the Muscles Two WeeksAfter Transplantation

Histology of the rats' hind limb muscles two weeks followingtransplantation using immunostaining with specific antibodies revealedhigh levels of BDNF, GDNF, IGF-1, and VEGF in MPCs-NTFs and theirsurrounding muscles tissue. There was no sign of tumor formation in thetransplanted area (FIG. 6A-D).

Example 6 MPCs-NTFs Delayed Motor Function Reduction in Treated SOD1Transgenic Mice

The mice motor performance was evaluated by the rotorod test once aweek, beginning at 70 days of age. At 70 days, there was no significantdifference among experimental groups. The mice were transplanted on day90 and 110 and the motor function was followed every week on rotarod. Inthe control group (PBS injections) the average of 50% reduction in theperformance on rotarod can be seen on day 116 comparable to the MPC-GFPand MPC-GDNF (115 and 116 respectively). However, the 50% reduction inmotor function in the mice transplanted with a mixture of all four NTFtransfected MPCs was significantly delayed to the age of 124 days.Notably this effect was found only in the females groups while the malegroups show similar behavior (FIGS. 7A-B).

Example 7 MPCs-NTFs Prolonged Life Span of Treated SOD1 Transgenic Mice

Life spans of SOD1 transgenic mice rats transplanted with a mixture ofall four NTF transfected MPCs were significantly prolonged compared witheither Saline/MPCs-GFP or MPCs-GDNF treated SOD1 mice. SOD1 transgenicmice rats transplanted with a mixture of all four NTF transfected MPCslived an average of 137.64+2.19 days, whereas saline/MPCs-GFP orMPCs-GDNF treated mice lived an average of 129.58+1.46; 125.38+1.47;129.4+0.92 respectively. Notably this effect was demonstrate only infemales (FIGS. 8A-B).

In another experiment mice were obtained by breeding SOD1 mice fromJackson laboratories (based on SJL strain background) with C57/bl mice.These mice are more suitable for transplantation with the geneticallymodified mouse MPC which were isolated from ROSA-26 mice which expressubiquitously Beta-gal and share C57/B1 background. In order to increasethe efficiency of incorporation of the inoculated cells intomultinucleated fibers, the muscles were preconditioned by injection ofminimal amounts of cardiotoxin, delivered one day prior totransplantation. This treatment enhances fusion of the transplanted MPCwith host myogenic cells, forming post mitotic multinucleated fibers.Indeed, these modifications dramatically improved the efficiency of theMPC-MIX. Higher performance on rotarode of the MPC-MIX transplanted micegroup was observed as compared to the saline treated mice (FIG. 9A).Moreover, a significant delay in the onset of the symptoms (defined asmore than 20% reduction on rotarod) in mice transplanted with theMPC-MIX was observed. While in the saline-treated group less than 50% ofthe mice are free of symptoms on day 109, in the MPC-MIX treated mice50% of mice are free of symptoms at least 39 later, on day 150 (FIG.9B).

Example 8 MPC-NTF Conditioned Media Synergistically Increase AKTPhosphorylation

In order to study the possible synergistic effect of the MPC-MIX on aknown signal transduction pathway, the present inventors focused on thePI3K-AKT pathway which is involved in cell survival, followingapplication of the four NTFs conditioned media. Thus, motor neuron cellline (NSC-34) were placed in a hypoxic environment for 24 hours in thepresence of conditioned media of each of the cloned MPCs expressing oneof the four NTF, MPCs-MIX+, or control growth medium. After 24 hours,cell's protein extraction was subject to Western blot analysis for theratio of AKT vs. phosphorylated-AKT proteins. The ratio was calculatedfor each treatment (FIG. 10). This analysis demonstrated thatphosphorylated AKT was undetectable in the untreated cells (controlmedium) while the ratio in the presence of MPC-BDNF/GDNF/IGF-1 was 0.11,0.09 and 0.12 respectively. In contrast, the MPC-MIX treatment increasedthe phosphorylated AKT ratio to 6-8 folds higher (0.73).

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Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

All publications, patents and patent applications mentioned in thisspecification are herein incorporated in their entirety by referenceinto the specification, to the same extent as if each individualpublication, patent or patent application was specifically andindividually indicated to be incorporated herein by reference. Inaddition, citation or identification of any reference in thisapplication shall not be construed as an admission that such referenceis available as prior art to the present invention. To the extent thatsection headings are used, they should not be construed as necessarilylimiting.

What is claimed is:
 1. An isolated cell population, comprising at leastfour subpopulations of human muscle progenitor cells, each of the atleast four subpopulations being distinct in that they are geneticallymodified to express a different neurotrophic factor, wherein theneurotrophic factor is selected from the group consisting of glialderived neurotrophic factor (GDNF), insulin growth factor (IGF-1),vascular endothelial growth factor (VEGF) and brain-derived neurotrophicfactor (BDNF).
 2. The isolated cell population of claim 1, wherein saidmuscle progenitor cells comprise skeletal muscle progenitor cells. 3.The isolated cell population of claim 1, wherein each of said at leastfour subpopulations are present in substantially equal amounts.
 4. Theisolated cell population of claim 1, wherein each of said at least foursubpopulations is genetically modified to express a single neurotrophicfactor.